A two-dimensional array of vertical field effect transistors can be employed as access transistors for vertical conductive lines such as local bit lines of a three-dimensional memory device. Ideally, vertical field effect transistors need to provide a high on-current and a low off-current with a well-defined threshold voltage. Typical vertical field effect transistors have degradation in performance due to various factors, which include high leakage current and low on-current due to crystalline defects and limitation on the spatial extent of the depletion zone. Vertical field effect transistors providing superior performance are desired.